1. Field of the Invention
The invention is directed to a pivotally mounted articulated support arm.
2. Description of Related Art
Various operations carried out in workshops and auto body repair shops require provision of welding equipment and various related utilities, such as compressed air, electrical power, fume and dust extraction. It is desirable that access to welding equipment and utilities be provided as close as possible to the work site since exposed conduits, cables and hoses are susceptible to damage and pose a risk to workers. The sources of such utilities are often fixed or adjacent to a workshop wall (for example: electrical power, water and compressed air lines), or the source is difficult to move adjacent to the work site (for example: bottles of compressed gases, and welding power supplies).
In auto body shops for example, M.I.G. (metal arc inert gas) welding equipment is used to join sheet metal members. The welding equipment includes compressed gas cylinders, electric power sources, consumable welding wire spools and wire feeding equipment. In general moving such equipment adjacent to the work site is difficult and cumbersome. Consequently cables, and hoses from the welding equipment extend to the work site across the shop floor posing a risk to workers and subjecting the conduits to damage. Other operations such as grinding, and cutting may require electric and compressed air conduits. Since dust and welding fumes are generated dust and fume vacuum extraction hoses also extend across the shop floor between vacuum equipment and the work site.
All of the above conduits cause considerable cluttering and congestion of the work site. In addition sparks, melted metal globules and falling debris from welding, grinding and cutting of metal may damage the conduits. Winding and unwinding conduits involves significant labour and expose conduits to wear during repetitive operations.
To provide easy access to welding equipment in particular conventional devices provide overhead access through the use of an overhead travelling crane. The crane runs longitudinally on a runway and has a transverse travelling dolly from which is suspended various utility conduits including welding cables and conduits. This device is capable of supporting a relatively heavy load such as welding wire spools, welding wire feeders, and welding guns. Utility conduits such as compressed air lines, welding power supply conductors and welding gas lines may be suspended in a festoon along the crane runway and across the crane bridge between the travelling dolly and the stationary utility source. Such devices are relatively expensive, and require an open overhead space to operate (thus interfering with lifting cranes, for example). As such the devices are generally unsuitable for small shops. The shape of the conduit festoon changes significantly depending upon the position of the crane and dolly, thus altering the resistance to flow within fluid conduits. As a result the head loss due to fluid friction in vacuum conduits varies significantly depending upon the shape of the festoon. Uniformity of vacuum strength is preferred but not possible with such an arrangement. A festoon arrangement is also unsuitable for fume and dust extraction ducts, which are particularly used in welding operations since particles may accumulate in the lower portion of the festoon loops impeding air flow and inducing stress in the duct.
To provide ready access to utilities other than welding equipment, electrical cables and compressed air lines for example have been wound upon a spring loaded spool mounted to the ceiling above a work site in automobile shops, for example. The connecting outlet end of the conduit when not in use is retracted to a height at which it can be reached. When access to the utility conduit is required, the outlet end is connected to an electric or air powered tool and the conduit unwound from the spring loaded spool. Ratchet means maintain the conduit in position relative to the spool until released to rewind upon the spool. Such devices are suitable for relatively small diameter hoses or cables only due to practical size limitations of the spool and the winding diameter of the conduit. Access to the conduit for repairs or inspection is restricted due to the height at which the spool is mounted.
It is desirable, therefore, to provide a device which supports a load, such as welding equipment, and utility conduits, providing ready access to various utility outlets, while accommodating a variety of conduit sizes and types.
It is also desirable that such a device impose as little as possible upon the working area and upon the operation of adjacent shop equipment, such as lifting cranes, for example, and that the device be easily moved and stored in a compact retracted configuration.